constraint_eqn_046 Subroutine

   subroutine constraint_eqn_046(tmp_cc, tmp_con, tmp_err, tmp_symbol, tmp_units)
      !! Equation for Ip/Irod upper limit (TART)
      !! author: P B Lloyd, CCFE, Culham Science Centre
      !! args : output structure : residual error; constraint value;
      !! residual error in physical units; output string; units string
      !! Equation for Ip/Irod upper limit (TART)
      !! #=# tfcoil
      !! #=#=# fipir, cratmx
      !! and hence also optional here.
      !! Logic change during pre-factoring: err, symbol, units will be assigned only if present.
      !! eps : input real :  inverse aspect ratio
      !! fipir : input real : f-value for Ip/Irod upper limit
      !! ritfc : input real : total (summed) current in TF coils (A)
      !! plasma_current : input real :  plasma current (A)
      !! itart : input integer : switch for spherical tokamak (ST) models:<UL>
      !! <LI> = 0 use conventional aspect ratio models;
      !! <LI> = 1 use spherical tokamak models</UL>
      use physics_variables, only: eps, plasma_current, itart
      use constraint_variables, only: fipir
      use tfcoil_variables, only: ritfc
      implicit none
      ! cratmx : local real : maximum ratio of plasma current to centrepost current
      real(dp) :: cratmx
            real(dp), intent(out) :: tmp_cc
      real(dp), intent(out) :: tmp_con
      real(dp), intent(out) :: tmp_err
      character(len=1), intent(out) :: tmp_symbol
      character(len=10), intent(out) :: tmp_units

      ! if the machine isn't a ST then report error
      if (itart == 0) call report_error(10)
      cratmx = 1.0D0 + 4.91D0*(eps-0.62D0)
      tmp_cc =  1.0D0 - fipir * cratmx * ritfc/plasma_current
      tmp_con = cratmx * (1.0D0 - tmp_cc)
      tmp_err = plasma_current/ritfc * tmp_cc
      tmp_symbol = '<'
      tmp_units = ''

   end subroutine constraint_eqn_046